The chief minister had filed revised I-T returns for assessment years 2008-09, 2009-10 and 2010-11, where his income showed about 14 times increase from Rs 47.35 lakh to Rs 6.56 crore.
The income tax case against Singh was reopened following the revised IT returns were challenged in Delhi High Court through a PIL.
The BJP had raised this issue during the last Assembly polls and again raked up the issue and also demanded a CBI probe into the financial transactions of Singh.
The I-T department has also questioned the LIC agent Anand Chauhan who managed orchards of Virbhadra Singh and sold the apples on his behalf and got the money.
Former Himachal Pradesh chief minister PK Dhumal also raised the issue in his letter to Sonia Gandhi yesterday and said that "the people of Himachal want to know the formula by which the income from orchards increased from Rs 47.35 lakh to Rs 6.56 crore in three years".